Synthesis, DNA binding, and cytotoxicity activity of bis-naphalenyl compounds with different diamine linkers

Multi-spectroscopic, calorimetric and molecular dynamics evaluation on non-classical intercalation of antiviral drug Molnupiravir with DNA

The interaction of an antiviral drug Molnupiravir (MOL) with calf thymus DNA (CT-DNA) was investigated using a series of biophysical techniques. A significant hyperchromism with a blue shift  nm in the UV-Vis spectra indicated a high binding affinity of MOL for CT-DNA with binding constants in the order of 105 M-1. Competitive fluorescent dye displacement assays with ethidium bromide (EB) and Hoechst 33258 suggested an intercalative mode of binding of MOL with CT-DNA. Thermodynamic profiles determined using fluorescence titration and isothermal titration calorimetric (ITC) analysis matched well with each other. The negative free energy change revealed that the MOL/CT-DNA complexation is a spontaneous process. The negative values of enthalpy and entropy changes indicated that H-bonding and van der Walls interactions play dominant roles in stabilizing the complex. A decrease in viscosity of CT-DNA solution upon adding MOL indicated a partial intercalation mode of binding which was well supported by circular dichroism (CD) spectral and effect of KI and denaturation studies. Molecular docking and metadynamics simulation studies clearly showed the partial intercalation of the pyrimidine ring of MOL into the base pairs of DNA. Free energy surface (FES) contour indicated that the drug/DNA complex is stabilized by H-bonding and pi-pi/pi-cation interactions.Communicated by Ramaswamy H. Sarma.

Synthesis, DNA binding of bis-naphthyl ferrocene derivatives and the application as new electroactive indicators for DNA biosensor

A series of bis-naphthyl ferrocene derivatives were synthesized and characterized. Based on the results obtained from UV-visible absorption titration and ethidium bromide (EB) displacement experiments, it was observed that the synthesized compounds exhibited a strong binding ability to dsDNA. In comparison to the viscosity curve of EB, the tested compounds demonstrated a bisintercalation binding mode when interacting with CT-DNA. Differential pulse voltammetry (DPV) was employed to assess the binding specificity of these indicators towards ssDNA and dsDNA. All tested indicators displayed more pronounced signal differences before and after hybridization between probe nucleic acids and target nucleic acids compared to Methylene Blue (MB). Among the evaluated compounds, compound 3j containing an ether chain showed superior performance as an indicator, making it suitable for constructing DNA-based biosensors. Under optimized conditions including probe ssDNA concentration and indicator concentration, this biosensor exhibited good sensitivity, reproducibility, stability, and selectivity. The limit of detection was calculated as 4.53 × 10-11 mol/L. Furthermore, when utilizing 3j as the indicator in serum samples, the biosensor achieved satisfactory recovery rates for detecting the BRCA1 gene.